Active Combustion Instability Control (ACIC) is the approach in which a combustion process is controlled by modifying the pressure within the system. This is done by sensing the amplitudes and frequencies of acoustic pressure waves and then modulating fuel injection at a frequency which dampens the naturally occurring thermo-acoustic instabilities. Over the past decade, research into active combustion control has yielded impressive results in suppressing thermo-acoustic instabilities and widening the operational range of gas-turbine combustors.
A known hurdle to effective implementation of the active combustion control is the availability of valves and actuators that provide adequate flow modulation control authority at low fuel flow rates. Recent valve technology focuses on the valves designed to modulate the entire fuel flow to the main combustor. These are large valves that must be located in a benign environment to operate properly. This location limits flow control authority for low flow rates when located far from the harsh thermal environment of a fuel injector.